Transport problems as perceived by inner city firms

The role of transport policy in assisting inner city firms is still unclear. This paper raises several important policy questions and reviews the findings of past research, which suggest that transport problems are a major irritant to inner city firms but are unlikely to cause them to leave the area, and that the ability of transport improvements to attract new firms is uncertain.It describes and presents the results of a recent study designed to determine the effect of transport problems on manufacturing and service industries, whether such problems are more serious in the inner city, and which solutions would be most appropriate. The study involved a series of detailed case studies of inner and outer city firms in Leeds and London. It identified as the most serious problems, congestion, public-transport problems, parking shortages and on-site delays for commercial vehicles. Similar problems arose in all areas, but were more severe in inner than in outer areas, and in London than in Leeds.The most common effect was lost time, but reduced efficiency, lost business, staff dissatisfaction and recruitment problems also occurred. Management had difficulty costing the effects of such problems, and often overlooked those incurred by others. The problems were, for the most part, local or site-specific, and are likely to be amenable to low-cost solutions. However, congestion and parking problems in inner London appear to merit area-wide treatment.A series of recommendations is provided for policy-makers.Further details of the study reported here are contained in a series of working papers which are available from the Institute for Transport Studies, University of Leeds.     

The metropolitan planning organization role in the 1980s

A new study by the U.S. Advisory Commission on Intergovernmental Relations focuses on the adaptions in transit services, finances, institutions, and policy processes occasioned by current financial stress at all levels of government and by the devolution of national responsibilities to the state and local governments. This study found, in part, that (1) most metropolitan transportation planning organizations now are locally governed and staffed. (2) their planning is becoming increasingly isolated, less comprehensive, and shorter range. (3) some such organizations are experiencing strong pressure to decentralize or subregionalize, and (4) the desire for these organizations to exercise more effective areawide leadership is not matched with local approval of greater powers for them. The study concludes that informal coordination techniques or new powers granted by state legislatures are the two most likely facilitators of improved metropolitan transportation leadership in the 1980s.     

The Application of Linear Optimal Control Theory to the Design of Active Automotive Suspensions

Some linear stochastic control theory relevant to the design of active suspension systems subject to integrated or filtered white noise excitation is reviewed, and application of the theory to a particular problem is considered. The problem considered is the well known quarter car problem in which a control law which minimises a performance function representing passenger discomfort, suspension working space, and tyre load fluctuations is required. With full state feedback, the requirement for a formulation of the problem which leads to the system under consideration being observable and controllable is referred to, and it is shown how a well known coordinate transformation enables this requirement to be satisfied. With limited state (or output) feedback, problem formulations which will avoid potential numerical problems in deriving the optimal control are described. Example solutions are included in order to illustrate the methods.     

Off-Road Vehicle Dynamics

Recent developments in off-road vehicle dynamics are reviewed. Progress on this topic and the application of new techniques to the particular problemsassociated with off-road operation tend to lag behind practices established for road vehicles.

The factor which limits further progress is the lack ofappropriate off-road tyre data, in particular, on vibrational and lateral force generation characteristics. Also, a long term study should be aimed at understanding the dynamic behaviour of tyres on yielding surfaces.     

南村黄河大桥空心薄壁高墩抗震分析

通过对小浪底水利工程中南村黄河大桥高墩进行抗震分析，研究了墩顶活动支座摩擦、基础弹簧约束对地震反应的影响。     

Heave-Pitch-Roll Dynamics of Flexible Vehicle in Variable Velocity Run

Analysis for response statistics evaluation of a flexible vehicle travelling with variable velocity over nonhomogeneously profiled flexible track is presented with a heave-pitch-roll model. The vehicle body is idealised as a flexible member with variable cross-section, inertia, damping and stiffness distributions. The vehicle may also have variable section slender elastic attachments. Coupled dynamics with rigid body heave-pitch-roll modes and elastic bending-torsion modes of the vehicle body along with coupled bending-torsion modes of the attachments are considered. Equivalent linear suspension system characteristics are employed for developing the analysis. Numerical results are presented for an aircraft with tricycle landing gear arrangements and comparison is made with other models.     

Driver response to variable message signs: a stated preference investigation

This paper uses a Stated Preference approach to undertake a detailed assessment of the effect on drivers’ route choice of information provided by variable message signs (VMS). Although drivers’ response to VMS information will vary according to the availability of alternative routes and the extent to which they are close substitutes, our findings show that route choice can be strongly influenced by the provision of information about traffic conditions ahead. This has important implications for the use of VMS systems as part of comprehensive traffic management and control systems. The principal findings are that the impact of VMS information depends on: the content of the message, such as the cause of delay and its extent; local circumstances, such as relative journey times in normal conditions; and drivers’ characteristics, such as their age, sex and previous network knowledge. The impact of qualitative indicators, visible queues and delays were examined. It was found that not only is delay time more highly valued than normal travel time, which is to be expected, but that drivers become more sensitive to delay time as delay times increased across the range presented.